Summary On 27July2004, at 0445 eastern daylight time, the Canadian tug Salvor, pushing the single-hull tank barge KTC115, loaded with approximately 9117 metric tons of liquefied calcium chloride was exiting American Narrows at Alexandria Bay, New York, United States, when it experienced a steering failure that shifted the rudder hard to starboard. A chain securing the starboard face wire failed, causing the tug to break free from the barge. The barge continued downstream and grounded on the north side of the channel, spilling approximately 60tonnes of calcium chloride. Ce rapport est galement disponible en franais Other Factual Information Particulars of the Vessels Description of Tug and Tow The Salvor is of conventional design with the wheelhouse forward and an upper wheelhouse located approximately 45feet above the waterline. The main towing winch is located aft of the accommodation on the main deck. The KTC115is a single-hull tank barge with 10tanks (five port and five starboard) with a total capacity of 11176 tonnes. The barge is equipped with a notch aft into which the tug is fitted when in the pushing mode. A single danforth anchor is located forward. If the barge becomes separated from the tug, the anchor cannot be dropped remotely. Photo1. Tug Salvor pushing barge KTC 115 Description of the Voyage On 24July2004, the Canadian tug Salvor, pushing the single-hull tank barge KTC115, loaded with approximately 9117tonnes of liquefied calcium chloride, departed Amherstburg, Ontario, bound for Montral, Quebec. As per company procedures, the crew tested and visually inspected the steering gear before departure, and found it to be satisfactory. Due to weather conditions, the barge was separated from the tug, and towed across Lake Erie. Before entering the Welland Canal, the tug re-assumed its pushing position in the notch of the barge. After passing through the Welland Canal, the passage across Lake Ontario was conducted with the Salvor pushing the barge KTC115. On July27, at 0445 eastern daylight time,2 the tug/barge, on autopilot and under the conduct of the mate, who was officer of the watch (OOW), was exiting American Narrows at Alexandria Bay, New York, along the south side of the river when a loud thump was heard from the aft part of the tug, following which the barge took a slight sheer to port. The deckhand on watch in the wheelhouse was sent to investigate the source of the noise, and the OOW attempted to correct the perceived swing to port. When the vessel did not respond, the OOW attempted to override the autopilot, switched to the backup hydraulic pump, and then to the non-follow-up (NFU) steering. When these systems proved ineffective, he called the master and the engine room to report that the steering had failed. The tug's stern swung further to port, parting the 2-inch hawsers securing the vessel to the notch of the barge. The tug swung free of the notch, heeled sharply to port, and was dragged backwards by the port face wire. The wire was kinked across a sharp edge of the bulwark and subsequently parted, releasing the tug. Subsequently, the crew found that the chain connecting the starboard face wire to the tug had parted. Arriving on the bridge, the master called the approaching tanker Thalassa Desgagnes (laden with heavy fuel oil), informing them that the tug had separated from the barge and that he did not have control of the barge. The master then placed a radio call to Seaway Clayton apprising them of the situation. Seaway Clayton then contacted the Salvor requesting clarification. Free of the tug, the barge continued downstream and grounded on the north side of the channel adjacent to Imperial Island in position 4420'25N, 07555'30W. During this time, the crew of the Salvor was unaware of the position of the barge until it was located by the passing Thalassa Desgagnes. Figure1. Sketch of the occurrence area with the tank barge KTC 115 aground In the engine room, the chief engineer took steering control and switched the engine room control first to emergency and then to the NFU steering. However, the rudder did not respond to commands. Steering with engines, the tug proceeded to the south side of the channel near the entrance to Alexandria Bay. When the chief engineer inspected the steering gear, he found that the telemotor feedback rod had broken. Following the installation of a temporary replacement rod, steering was regained and the vessel proceeded across the channel to locate the barge. After sending out crew members in a small boat to take soundings around the grounded barge, the Salvor proceeded to reconnect to the barge. Traffic was suspended in the American Narrows area of the St. Lawrence Seaway from the time of the occurrence until 1820 on the same day. Photo2. KTC 115 aground at Imperial Island Environmental Conditions At the time of the occurrence, the wind was calm and visibility was six miles in intermittent showers. The vessel was proceeding along the extreme southern edge of the channel in approximately 8m of water. Damage to the Vessels A damage survey of the barge by divers revealed inset bottom plating and three cracks in the bottom of the forward-most starboard tank. A rope was found entangled in the port propeller of the tug, and the tips of the starboard propeller blades were found to be damaged. Damage to the Environment By the time measures had been instituted to stop the egress of cargo, approximately 60tonnes of calcium chloride solution was released into the river. The spill was unrecoverable; however, responders judged that it posed no threat to the environment. Vessel Track Before the Occurrence In accordance with Seaway regulations,3 the Salvor was equipped with an automated identification system (AIS) that transmitted data including vessel speed, position, and identity to both Seaway Traffic Control, and to other vessels in the vicinity. As the Salvor/KTC115 exited American Narrows just west of Alexandria Bay, the Thalassa Desgagnes was approaching upbound 1km to the east. Following the occurrence, a copy of the St. Lawrence Seaway Management Corporation (SLSMC) electronic traffic control recordings of the Salvor's track before and during the occurrence was obtained. The Salvor's displayed position on the SLSMC playback was of poor quality and lacked accuracy. Subsequently, an electronic download from the electronic chart system (ECS) installed on the Thalassa Desgagnes was obtained, which accurately showed the track of the Salvor for several hours leading up to the occurrence. Information from the playback indicated that, at the time of the occurrence, the vessel was at the extreme south side of the channel passing over the edge of a shoal extending outwards from Cherry Island. Crew Qualifications and Experience The master held a valid certificate for master, ship of not more than 350tons, gross tonnage, or tug, local voyage, issued by Transport Canada (TC) in June2004. He graduated from the Georgian College marine program in 2002. All of his sea experience had been obtained with McKeil Marine Limited. In accordance with the Great Lakes Pilotage Regulations,4 he had been granted an exemption from taking a pilot aboard. This assignment to the Salvor/KTC115 was the master's first experience as captain and his first experience on board the combination of Salvor/KTC115. The mate had worked for McKeil Marine Limited for 10years and had approximately one month of experience on board the Salvor/KTC115. He held a valid certificate for restricted watchkeeping mate, issued by TC in September1999, and had been granted a pilotage exemption. The chief engineer held a valid certificate for first-class engineer, motor ship, issued by TC in January1999, and had worked for two months with McKeil Marine Limited on board the Salvor. Vessel Certification and Inspection The Salvor was imported into Canada from the United States in August2000 and had been inspected and certified by TC for home trade, ClassII voyages. The most recent annual inspection of the vessel was conducted on 02October2003. This inspection included an operational test of the steering gear since the next four-year periodic inspection was not due until July2005. The barge KTC115was imported from the United States and registered in Canada on 16June2003. The barge had been classed by the American Bureau of Shipping (ABS) under its previous ownership; however, its classification had lapsed at the time of the occurrence. It was subsequently inspected by TC in April2004 and was issued a temporary load line certificate on 29July2004. Domestic Canadian and United States vessels, which are trading inland and are not International Safety Management Code (ISM Code)certified, are required to undergo an inspection by either the SLSMC or the Saint Lawrence Seaway Development Corporation (SLSDC) every two years. Conventional tug/barge units such as the Salvor/KTC 115 are required to be inspected before every Seaway transit.5 Consequently, the Salvorwas inspected and approved for passage by the SLSMC during a transit of the Welland Canal on 22July2004. However, as the KTC 115 was inspected by the Seaway in 2003, at which time it was still in class, it was not due for another Seaway inspection until 2005. As a result, the scope of the Seaway inspection did not include the KTC115. The Salvor's steering gear was functionally tested in all modes from the wheelhouse. The inspection noted the following deficiencies: a compass deviation card was not on board, charts and publications/Seaway notices were not up to date, the rudder angle indicator in the wheelhouse was defective, and the steering station in the engine room lacked a rudder angle indicator. Three of these were cleared before 26 July 2004, while one remained to be cleared in 15days. With respect to crewing, Seaway regulations require that, while transiting the sections of Montral to Lake Ontario and Welland Canal, the wheelhouse of the ship be crewed at all times by either the master or certified deck officer and by another qualified crew member, and that sufficient, well-rested crew members be available for mooring operations and other essential duties.6 At the time of the SLSMC inspection, the complement on board the Salvor consisted of a master, mate, chief engineer, second engineer, three deckhands, pumpman, and cook. The master and mate, and chief and second engineer each stood watch six hours on, six hours off. The three deckhands stood watch four hours on, eight hours off. The cook and the pumpman were day workers and did not stand a watch. Connection of the Tug to the Barge The towing arrangement comprised a notch in the transom of the barge that housed the bow of the tug (see Photo 1). The securing arrangement comprised a 2-inch braided polypropylene hawser from the bow of the tug to a bitt on the barge and similar hawsers, one at each corner of the barge's notch to the port and starboard shoulder of the tug (see Figure2). To facilitate steering and backing, single 1-inch-diameter, 636 face wires were rigged between quarter bits on the barge and the after deck of the tug. The starboard wire was shackled to a 2-inch steel stud chain, which, in turn, was shackled to a fairlead mount on the deck of the tug. The port face wire was connected through a fairlead to the tug's towing winch that was used to tension the tug in the notch. Figure2. Arrangement of connection between the Salvor and the KTC 115 Photo3. Arrangement of chain connecting starboard facewire Post-occurrence examination of the rigging found that two links of the chain connecting the starboard face wire had failed, and that the port face wire had also parted at the point where it would normally lead through the port bulwark fairlead. Tests on the failed chain links indicate that they failed from sudden overstress.7 The tests found that there were no significant corrosion or defects in the failed chain links and that the breaking strength was consistent with standards for that size chain. No certification, inspection, or maintenance records were available on board for either the chain or wire, although a certificate from the wire rope manufacturer was produced by the owner some three months after the occurrence. The history of the failed chain could not be determined by the company; however, it was in poor overall condition with studs loose or missing from some links. Indications are that it probably came from a marine salvage yard. The size of the face wires was chosen by the company based on tables provided by the Oil Companies International Marine Forum. The complete design of the physical connection between the Salvor and the KTC115 (including the chain and bow notch connection), and the handling characteristics of the mated pair were not subject to any formal analysis by the owner, TC, or the SLSMC/SLSDC, nor were they required to be by regulations. Although the condition of the tow line was visually checked by the SLSMC/SLSDC during its inspection on 22July2004, the condition of the tackle used in the connection was not verified by TC, nor was it required to be by regulation. Steering System The Salvor is equipped with an electro-hydraulic steering system powered by two independent electrically driven hydraulic pumps in the engine room. The steering gear is comprised of two hydraulic rams that are connected to rudder quadrants via one-inch-diameter, 6 x 36 wire-core wire rope. Control of the steering is provided by follow-up ComNav101 remote control and NFU electrical control systems that actuate solenoid valves to direct oil to the appropriate hydraulic ram. Follow-up rudder position sensing is achieved by means of a brass telemotor feedback rod connected to an electronic rudder position sensor. Post-occurrence inspection of the system revealed that the telemotor feedback rod had failed at the adjustable threaded toggle connecting it to the rudder quadrant. Laboratory examination of the failed rod showed that it failed from damage due to fatigue.8 The pivot pin that transmits the quadrant motion to the telemotor feedback rod was misaligned, and the rod was found to bind as the rudder moved between midships and hard over position in each direction. The mounting of the pivot pin on which the rod mounts had been modified at some time in the past; however, no records were available to indicate when and by whom. Tests of the steering system showed that both the bridge rudder angle indicator and the NFU steering system did not function when the telemotor feedback rod was disconnected. Photo4. Misaligned pivot pin connecting telemotor rod tostarboard rudder quadrant Since being imported into Canada in 2000, the Salvor has experienced at least three steering-related incidents. On 28November2001, a steering cable separated while the vessel was transiting the St. Lawrence Seaway. On 05October2002, a steering cable slipped off a rudder quadrant due to excess free play. More recently, in June2004, during a voyage to New York, the crew discovered that a steering cable had become slack. Post-occurrence inspection of the system on July27 revealed that the steering cables had deteriorated, and TC requested that they be replaced. Subsequent laboratory examination indicated that the steering cables had deteriorated from in-service fatigue.9 Company Safety Management The company had adopted the ISM Code on one of its tug/barge combinations that was on a dedicated charter carrying jet fuel. While the company had not applied the ISM Code safety management system (SMS) to other vessels in the fleet, some documented procedures had been developed and introduced fleet-wide including a written policy and procedure for navigation in confined waters. This procedure did not address the use of the autopilot. In addition, the company had implemented an internal system for reporting and following up on marine occurrences.